Force dividing linkage for mechanically held electromagnetic contactor



p 9, 1969 o. F.- LETOSKY ETAL 3, 7

FORCE DIVIDING LINKAGE FOR MECHANICALLY HELD ELECTROMAGNETIC CQNTACTORFiled Aug. 17, 1967 3 Sheets-Sheet 1 elil P 9, 1969 D. F. LETOSKY ETAL3,465,577

FORCE nxvnmw LINKAGE FOR MECHANICALLY HELD ELECTROMAGNETIC CONTACTORFiled Aug. 17, 1967 5 Sheets-Sheet 2 United States Patent 3,466,577FORCE DIVIDING LINKAGE FOR MECHANICAL- LY HELD ELECTROMAGNETIC CONTACTORDonald F. Letosky, Detroit, and Elwood T. Platz, Grosse Pointe Farms,Mich., assignors, by mesne assignments, to I-T-E Imperial Corporation,Philadelphia, Pa., a corporation of Delaware Filed Aug. 17, 1967, Ser.No. 661,293 Int. Cl. H01h 9/20 US. Cl. 335-167 6 Claims ABSTRACT OF THEDISCLOSURE A mechanical latch designed for operation with a relativelysmall size electromagnetic contactor is connected for operation with arelatively large size contactor by utilizing a force dividing latchlever pivotally mounted at one end thereof to a fixed portion of thecontactor. With the contactor mechanically latched, a point intermediatethe ends of the lever, and preferably close to the pivot, engages theportion of the contactor carrying the movable contacts. The end of thelever remote from the lever pivot is engaged by the mechanical latchwith this engagement being through a pawl pivoted to the lever andprovided because of a space limitation.

This invention relates to electromagnetic contractors in general andmore particularly relates to means for enabling a relatively small sizemechanical latch to be utilized with a relatively large size contactor.

Mechanically held contactors are utilized where absolute quietness isrequired or where the customary hum from magnetically held contactorswill be objectonable. The J. H. Herrmann et al. copending applicationSer. No. 518, 366 filed Jan. 3, 1966, now Patent No. 3,358,252 andassigned to the assignee of the instant invention discloses amechanically held contactor with manual release. The latch unit of theaforesaid application Ser. No. 518,366, now Patent No. 3,358,252, isspecifically adapted to be utilized with relatively small sizecontactors. For reasons of economy it is desirable to utilize this samerelatively small size latch unit with relatively large sizeelectromagnetic contactors. However, such relatively small size latchunits will not function when in direct engagement with the movablecontact carrier of a relatively large size contactor because of thecombined forces of the return springs and contact pressure springs istoo large.

The instant invention consists of utilizing a force dividing linkage toreduce the force reflected from the contactor back to the latch unit. Inparticular, the force dividing linkage is a lever pivotally mounted atone end thereof to a fixed portion of the contactor and is provided witha latching portion which engages the movable contact carrier. Because ofspace limitations a pawl pivotally mounted to the end of the leverremote from the contactor is interposed between the lever and themovable contact carrier.

Accordingly, a primary object of the instant invention is to providenovel means which permits a relatively small size mechanical latch unitto be utilized with a relatively large size electromagnetic contactor.

Another object is to provide a force diving linkage interposed between arelatively large size electromagnetic contactor and a relatively smallsize electromagnetically releasable latch means.

Still another object is to provide a linkage of this type mounted to thecontactor on a fixed pivot and having a pawl mounted on the other endthereof to be directly engaged by the latch unit.

These as well as other objects of this invention will be- 3,466,577Patented Sept. 9, 1969 come readily apparent after reading the followingdescription of the accompanying drawings in which:

FIGURE 1 is a side elevation showing a relatively small size mechanicallatch unit and a relatively large size electromagnetic contactor inoperative relationship with a force dividing linkage interposedtherebetween in accordance with the teachings of the instant invention.

FIGURE 2 is a side elevation showing the elements of the force dividinglinkage in the positions occupied thereby when the contactor is latchedclosed.

FIGURE 3 is a plan view of the elements of FIGURE 2 looking in thedirection of arrows 3-3 of FIGURE 2.

FIGURE 4 is an exploded perspective of the significant elements ofFIGURE 2.

FIGURES 5 and 6 are schematics showing the major elements of the devicesin FIGURE 1. In FIGURE 5 the, contactor is latched closed while inFIGURE 6 the contactor is open.

Now referring to the figures. Electromagnetically releasable mechanicallatch unit 10 of FIGURE 1 is of the identical size and shape as thelatch unit illustrated in the aforesaid copending application 518,366,now Patent No. 3,358,252. However, electromagnetic contactor 11 to whichlatch unit 10 is mounted is many times larger in size than the contactorof the aforesaid copending application 518,366, new Patent No.3,358,252. In fact, the contact pressure springs 12 (FIGURES 5 and 6)and the movable contact carrier return springs 13 are so massive thatthe forces exerted thereby will not permit latch unit 10 'to functionproperly when latching extension 14 thereof is in direct engagement withthe movable contact carrier 15. Thus, a force reducing linkageconsisting of lever 17 and pawl 18 is interposed between latch unit 10and movable contact carrier 15.

More particularly, lever 17 consists of elongated arm portion 21, latchportion 22 in a plane parallel and offset with respect to arm 21,connecting section 23 perpendicular to and joining arm 21 to latchsection 22, and bearing section 24 also offset from and parallel to arm21. Rivet 25, extending through aligned apertures 26, 26 in arm 21 andcar 24 as well as through clearance aperture 27 in car 28 of mountingbracket 30, provides a pivotal mounting for lever 17 at one end thereof.Main portion 29 of bracket 30 is at right angles to ear 28 and isprovided with clearance apertures 31 which receives screws 32 fixedlysecuring bracket 30 to a stationary portion of contactor 11. One. end33a of torsion spring 33 engages tab 290: of bracket 30 while the otherend 33b of spring 33 engages connecting portion 23 of lever 17. Spring33 is Wound about pivot 25 and is positioned in the space between arm 21and ear 24 to bias lever 17 in a counterclockwise direction, as seen inFIGURE 2, about pivot 25 as a center.

Rivet 36 pivotally mounts one end of pawl 18 to the ends of lever 17remote from pivot 25 with this pivotal movement being limited because ofthe relative proportions of lever 17 and pawl 18. The end of pawl 18remote from pivot 36 is provided with section 37 in a plane parallel torivet 36 and positioned so that the edge thereof most remote from rivet36 is engageable by projecting part 14 of latch unit 10 for latchingcontact 11 closed. Rounded embossment 37a extending rearward fromsection 37 is engageable with latch unit surface 10a during movement oflever 17. Nose 37b projecting at right angles from section 37 isengageable with fixed surface 11a of contactor 11 during pivoting oflever 17.

Latching part 22 of lever 17 is provided with notch 22a to receive edgeportion 38a of extension 38 for member 40 which is fixedly secured tomovable contact carrier 15 and retains movable armature 41 mounted tocarrier 15. Projection 41a at the end of member 40 remote from extension38 projects opposite to the projecting direction of extension 38 and, asis now well known in the art, in cooperation with a suitably shaped slotprovides guidance for carrier 15 as contactor 11 is opened and closed.

With the elements previously described in the positions occupied whencontactor 11 is open (FIGURE 6) movable contacts 51, 53 are separatedfrom stationary contacts 52, 54, respectively. When contactor coil 55 isenergized armature 41 is attracted and moves downward to the contactorclosed position of FIGURE 5. This causes movable contact carrier 15 andall elements secured thereto to move downward. Initially, the motion ofcarrier extension 15a is transmitted to contacts 51, 53 through spring12 but once contacts 51, 53 engage contacts 52, 54 continued movement ofarmature 41 causes loading of contact pressure spring 12. The lattertends to move contact carrier 15 to the raised position shown in FIGURE6 wherein contactor 11 is open. By the time the contactor contacts areclosed, the upper edge'38a of extension 38 is opposite notch 22a inlatching part 22 of lever 17 so that spring 33 is elfective to causeslight counterclockwise movement of lever 17 to a position wherein edge38a is deep within latching recess 22a. Further, under these conditionsthe upper end of pawl 18 has moved below projecting part 14 of latchunit 10 so that spring 65 of latch unit 10 is free to drive projection14 to the right to the latching position shown in FIGURE 5.

When contactor coil 55 is deenergized, upward movement of movablecontact carrier 15 is blocked since latch unit extension 14 preventsupward movement of pawl 18 which in turn prevents clockwise rotation oflever 17. Since latching part 22 is much closer than pawl 18 to pivot26, the forces exerted by return springs 13, 13 and contact pressurespring 12 appear reduced when applied to latch unit projection 14.

In order to open contactor 11, coil 64 of latch unit 10 is energized andattracts armature 63 of unit 10 to the left with respect to FIGURE Thismoves the righthand edge of latch unit extension 14 to the left of pawl18. Now the forces of return springs 13, 13 and contact pressure spring15 are effective to rotate lever 17 in a clockwise direction about pivot25 and in so doing the position of recess 22a changes and latching partedge 22b moves to the left of extension 38 thereby permitting the latterto move upward opening the contacts of contactor 11. Pawl 18 also movesupward to a position blocking return of projection 14 to latchingposition upon deenergization of coil 64.

Thus it is seen that the instant invention provides force dividing meanswhereby return and contact pressure spring forces reflected back to amechanical latch are greatly reduced thereby permitting a relativelysmall mechanical latch unit to be operated in coordination with arelatively large size electromagnetic contactor.

Although there has been described a preferred embodiment of this novelinvention, many variations and modifications will now be apparent tothose skilled in the art. Therefore, this invention is to be limited,not by the specific disclosure herein, but only by the appending claims.

The embodiments of the invention in which an exclusive privilege orproperty is claimed are defined as follows:

1. The combination of an electromagnetic contactor unit and anelectrically releasable latch unit for maintaining said contactor unitclosed; said contactor unit comprising a fixed section and a movablesection, cooperating contact means having portions mounted to each ofsaid sections; said latch unit including a latching portion; meansbiasing said latching portion to a latching position and anelectromagnetic operator for moving said latching portion to a releasingposition; a lever means; pivot means movably mounting said lever meansto said fixed section; said lever means positioned and constructed tosimultaneously engage said latching portion and said movable sectionwhen said latching portion is in said latching position and said movablesection is in closed position wherein said contact means is closed withsaid latching portion blocking movement of said lever means to therebymechanically prevent opening of said contact means.

2. A combination as set forth in claim 1 in which said contactor unitincludes biasing means urging said lever about said pivot means as acenter, additional biasing means acting to cause relative movementbetween said sections to an open position wherein said contact means isopen; said additional biasing means exerting a greater force than saidbiasing means and in opposition thereto whereby the latter is overcomeand said movable section operates to said open position when saidlatching portion is in said releasing position.

3. A combination as set forth in claim 2 in which said lever includes alatch portion which engages said movable section; said pivot means beingat one end of said lever; said latch portion being intermediate the endsof said lever and closer to said one end than to the other end; saidlatching portion being operatively engageable with said lever at saidother ends.

4. A combination as set forth in claim 3 in which there is a pawlconnected to the other end of the lever and interposed between saidlever and said latching portion.

5. A combination as set forth in claim 4 in which the pawl is pivotallyconnected at one end thereof to the other end of the lever for relativemovement with respect to said lever.

6. A combination as set forth in claim 5 in which said fixed section andsaid latch unit having facing surfaces forming a narrow spacetherebetween wherein the other end of the pawl is disposed and confinedto limited movement with respect to said lever.

References Cited UNITED STATES PATENTS 1/1963 Landow 335- l/1968 Conner335-170

